Caractérisation des matières plastiques solubles en conditions normales de pression et de température : une déformulation nécessaire à leur recyclage chimique

The recycling of plastics is a major issue in the energy transition. These materials are widely used in many fields: packaging, automotive, household appliances, construction, agriculture, thus generating a significant amount of waste. Today, recycling is mainly done through mechanical recycling processes. The recycled plastic material can then sometimes be considered as "degraded" compared to equivalent virgin polymers in terms of intrinsic properties (purity, mechanical properties, etc.). Therefore, chemical recycling is seen as a beneficial alternative to mechanical recycling. Chemical recycling can take different forms: dissolution, depolymerization, or conversion. Whatever the recycling process used, the characterization of the input materials (plastics to be recycled) is essential. Indeed, plastics are generally composed of different polymers (polyolefins, polyesters, polyurethanes, etc.) to which are added organic and/or inorganic additives of various kinds (colorants, pigments, stabilizers, plasticizers, etc.). These can have an impact on the efficiency of the processes, therefore they must be clearly identified and quantified.
The deformation of plastics to be recycled is at the heart of this thesis whose objectives are mainly turned towards the characterization of plastic additives and their degradation products. 
The scientific approach will be based on the implementation of extraction, prefractionation and analysis methods based on the use of liquid chromatography combined with high resolution mass spectrometry and ion mobility spectrometry. This analytical approach generates a large volume of data whose exploitation will require the development of methodologies using chemometric tools.